Pressure washer systems are routinely used in wide variety of applications to remove debris, dirt, fluids and other substances from surfaces needed to be cleaned. For example, driveways, garage floors, concrete or tile patios, stairs, walkways, decks, home exteriors, fencing, cars and trucks, lawnmowers, dirt bikes, boats or trailers, outdoor furniture, and grills may benefit from being pressure washed. Commercial uses include factories, food processing plants or restaurants, agriculture equipment, construction equipment, earth moving equipment, and mining equipment, etc.
As can be imagined, it is sometimes desirable that the fluid being used to wash an item, such as water, water with chemicals or detergent added thereto, other chemical mixtures, etc. be heated to a certain temperature to help remove the undesirable substance that is clinging to a surface that needs to be cleaned. For example, some organic substances such as grease or fat are difficult to remove unless the temperature of the water used reaches a threshold emulsifying temperature. In some applications, it may be desirable that the water reach a certain temperature such as 120 degrees Celsius so that grease may be removed from a surface.
Often, a pressure washer system is supplied with a fossil fuel supply such as gasoline or diesel to fuel an engine, which powers a pump for expelling the water at the desired pressure. Also, the same fuel is often used as part of an ignition system that creates a flame that heats air that is blown through a heat exchanger, which in turn, heats the water and/or other cleaning fluids that are intended to clean a surface using the pressure washer system. As can be imagined, the amount of fuel burned while maintaining a desired temperature of the cleaning fluid may vary considerably depending on the efficiency of the heat exchanger. If the heat exchanger operates inefficiently, then the profit of a business endeavor using the pressure washer can decrease significantly. Also, emissions to the atmosphere may be increased.
In some applications, heated water or other cleaning fluid is not warranted. Regardless if a heat exchanger is used or if an internal combustion engine is used to power a particular pressure washer system, most pressure washer systems supply the water or other cleaning fluid at a suitably high pressure using a pump. If the supply of water or other cleaning fluid runs low, air may be sucked into the pump, which can cause damage to the pump as the pump may become overheated, experience cavitation, etc. If this occurs often enough or long enough, the pump may fail. This leads to downtime for the pressure washer system and associated economic losses for a business endeavor using that pressure washer system.
Similarly, if for some reason, the pressure at the pump inlet is negative for too long, air may be sucked into the pump, creating cavitation that might cause the pump to be damaged.
Accordingly, it is desirable to develop a low cleaning fluid shutdown system for use with a pressure washer system that decreases the likelihood of air being introduced into the pump, or otherwise decrease the likelihood of cavitation and the associated risk of damage to the pump.